This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Systemic lupus erythematosus (SLE) is a complex autoimmune disease that presents with a variety of clinical manifestations and affects all races, genders, and age groups. About 10% of SLE patients are diagnosed by age 18. SLE that has onset in childhood tends to be more severe and to have a more aggressive clinical course. Although numerous studies have been performed characterizing the genetics of SLE, none of them have focused on the pediatric-onset subgroup. We hypothesize that pediatric-onset cohorts will be enriched for genetic effect, and that the genetic risk factors found in this population will also confer risk in adult-onset SLE patients. We have previously collected three cohorts of pediatric SLE patients and matched controls, including clinical data, serum samples, and DNA. We plan to streamline our search for susceptibility genes in pediatric-onset SLE patients using the AFFymetix GeneChip, which allow simultaneous genotyping at 500,000 loci. Once the first phase of genotyping is complete, results will be compared with the database and priorities for the second phase of SNP typing will be established. The top 500 effects will be characterized in the second cohort of pediatric-onset SLE cases and controls. It is expected that only a subset of these effects will be confirmed, but those effects that can be replicated are likely to represent true SLE susceptibility loci, both in adults and children.